CHIP-SCALE OPTICALLY DETERMINED MAGNETIC RESONANCE SENSOR

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a continuation-in-part of U.S. patent application Ser. No. 18/190,526, filed on Mar. 27, 2023, the entire contents of which are incorporated by reference herein.

TECHNICAL FIELD

The subject matter described herein relates in general to optical detection of magnetic resonances and, more specifically, to a compact ODMR sensor for industrial or consumer applications.

BACKGROUND

Optical detection of magnetic resonances (ODMR) is a technique in which the fluorescence of a crystal defect arising from excitation by an optical signal may be affected by the presence of a magnetic field when the crystal defect is subject to microwave pumping at a resonant frequency. As such, based on evaluating the altered fluorescence, measurements of the strength and direction of the magnetic field may be obtained. A particular crystal defect of interest for ODMR is a nitrogen vacancy (NV) center.

SUMMARY

Embodiments of the present technology include an apparatus for measuring an external magnetic field or other external stimulus. This apparatus includes a solid-state host comprising a plurality of color centers, a photonic integrated circuit comprising optical modulators and a grating array in optical communication with the plurality of color centers via a material capable of transmitting light below 1000 nm, a semiconductor integrated circuit comprising a plurality of metal layers, a microwave antenna, and a photodetector in optical communication with the plurality of color centers.

Embodiments of the present technology include a device for measuring an external magnetic field or other external stimulus. This device includes a semiconductor integrated circuit comprising a solid-state host comprising a plurality of color centers, a photonic integrated circuit comprising optical modulators and a grating array in optical communication with the plurality of color centers via a material capable of transmitting light below 1000 nm, a semiconductor integrated circuit comprising a plurality of metal layers, a microwave antenna, and a photodetector in optical communication with the plurality of color centers.

Embodiments of the present technology include an apparatus for measuring an external magnetic field or other external stimulus. This apparatus includes a semiconductor integrated circuit, a photonic integrated circuit disposed on the semiconductor integrated circuit and providing an integrated optical path from a light source to a solid-state host via waveguides, optical modulators, and gratings in a material suitable for transmission of light below 1000 nm, and the solid-state host comprising a plurality of color centers disposed on an opposing side of the photonic integrated circuit relative to the semiconductor integrated circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate various systems, methods, and other embodiments of the disclosure. It will be appreciated that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one embodiment of the boundaries. In some embodiments, one element may be designed as multiple elements or multiple elements may be designed as one element. In some embodiments, an element shown as an internal component of another element may be implemented as an external component and vice versa. Furthermore, elements may not be drawn to scale.

FIG. 1 illustrates an example of an ODMR sensor for industrial or consumer applications.

FIG. 2 illustrates an example of an integrated device for ODMR.

FIG. 3 illustrates an example of a semiconductor integrated circuit as part of an integrated device for ODMR.

FIG. 4 illustrates an example of an NV material as part of an integrated device for ODMR.

FIG. 5 illustrates an example of a photonic integrated circuit as part of an integrated device for ODMR.

FIG. 6 illustrates an example of a photonic integrated circuit employing Mach Zehnder modulators and gratings.

FIG. 7 illustrates an example of a photonic integrated circuit employing ring resonator modulators and gratings.

FIG. 8 illustrates an example of a semiconductor integrated circuit incorporating permanent magnets as part of an integrated device for ODMR.

FIG. 9 illustrates an example of how permanent magnets may be used to bias ODMR measurements.

FIG. 10 illustrates an example of an integrated device for ODMR with a different microwave antenna location.

FIG. 11 illustrates another example of an integrated device as part of an integrated device for ODMR.

DETAILED DESCRIPTION

Systems and methods for an ODMR sensor suitable for industrial or consumer applications are described herein. An illustrative example of an integrated device for ODMR incorporating the systems and methods disclosed herein is presented in FIG. 1. As shown in FIG. 1, a reflective semiconductor optical amplifier (RSOA) laser may emit a green light that is distributed by a photonics chip adjacent to and optically coupled to an NV material containing NV centers. The green light when absorbed by the NV centers (which may also be referred to as color centers) may then cause red fluorescence. A semiconductor integrated circuit adjacent to and optically coupled to the NV material may contain photodetectors to detect the red fluorescence and a microwave antenna for applying microwave signals to the NV centers. Based on microwave pumping from a microwave antenna that may reside in the semiconductor integrated circuit, the frequency components of the red fluorescence may be evaluated to determine the strength and direction of an external magnetic field B. The ODMR sensor may contain an optical filter (e.g., a metamaterial filter) that allows the passage of red fluorescence to the photodetectors while rejecting the green light from the laser. In addition, the ODMR sensor may include a mirror on the top of the photonics chip to reflect green light back to NV centers or red fluorescence to the photodetectors.

Though not shown in FIG. 1, the photonic chip may use materials allowing for the transmission of light below 1000 nm, such as silicon nitride or silicon carbide, as compared to traditional silicon waveguides that are light absorbing below 1100 nm. The photonic chip may also use modulators, such as Mach Zehnder modulators, ring resonator modulators, or other modulators in conjunction with gratings to adjust the location and intensity of the optical signal as applied across the NV material. Another aspect not shown in FIG. 1 is that the semiconductor integrated circuit may include permanent magnets or a microwave generator and phase lock loop.

With respect to FIG. 2, an example of an integrated device for ODMR is shown. ODMR device 200 may be formed on a carrier PCB 210. ODMR device 200 may be comprised of a first layer (e.g., disposed on carrier PCB 210) in the form of semiconductor integrated circuit 230; a second layer disposed on the first layer in the form of an NV material 240, wherein the second layer is optically coupled to the first layer; and a third layer disposed on the second layer in the form of photonic integrated circuit 250, wherein the third layer is optically coupled to the second layer. ODMR device 200 may also comprise a microwave generator and phase locked loop (Microwave Generator/PLL) 220 electrically coupled to the first layer or integrated therein. ODMR device 200 may also comprise a light source 270 optically coupled to the third layer or integrated therein.

Semiconductor integrated circuit 230 may, as shown in FIG. 3, be comprised of a semiconductor integrated circuit 300 with a plurality of metal layers for generating microwave signals and performing photodetection. Semiconductor integrated circuit 300 may comprise a microwave antenna 320 in a first metal layer for transmitting microwave signals to NV Material 240. For example, the microwave antenna may be a coiled loop inductor with a resonance near 2.87 GHz. A microwave generator and phase locked loop (Microwave Generator/PLL 310) may be electrically coupled to microwave antenna 320. In some embodiments, Microwave Generator/PLL 310 may be a device residing on carrier PCB 210 and in electrical communication with microwave antenna 320. In other embodiments, Microwave Generator/PLL 310 may reside in one or more metal layers within semiconductor integrated circuit 300 rather than as a device residing on carrier PCB 210. Microwave Generator/PLL 310 may generate microwave signals near 2.87 GHz.

Semiconductor integrated circuit 300 may also comprise photodetectors 330 for detecting fluorescence from NV material 240. For example, photodetectors may be configured to detect fluorescence between 400 nm to 1100 nm (e.g., as may be provided by silicon photodiodes). In some embodiments, an optical filter may be applied on or within semiconductor integrated circuit 300 to filter out optical signals not resulting from fluorescence of color centers. For example, the optical filter may suppress green light (e.g., at 532 nm) from reaching photodetectors 330, while allowing a range of light (e.g., via a bandpass filter configured to pass 575 nm to 800 nm, via a bandpass filter with a bandwidth of 80 nm centered at 637 nm) resulting from the fluorescence of color centers to reach photodetectors 330. In some embodiments, permanent magnets may be applied on or within semiconductor integrated circuit 300, as described below, to provide a magnetic bias to NV material 240.

NV material 240 may, as shown in FIG. 4, be comprised of a solid-state host 400 comprising a plurality of color centers. For example, solid state host 400 may take form of NV material 410, comprising a diamond crystal lattice with NV centers 420 in the form of nitrogen vacancy defects distributed therein. For example, the NV material may be formed by use of chemical vapor deposition to form a diamond, which may have a small fraction of single substitutional nitrogen traps vacancies generated as a result of plasma synthesis. In some embodiments, irradiation by high-energy particles and annealing may also be used to enhance the presence of NV centers in a NV material. In some embodiments of NV Material 410, portions of the color center substrate may have an enhanced color center density or have a specific color center orientation.

Photonic integrated circuit 500 may, as shown in FIG. 5, be comprised of a photonic transmission, modulation, and distribution layer for providing an integrated optical path between a light source and the NV material 240. For example, photonic integrated circuit 500 may be optically coupled to light source 530, such as via photonic integrated circuit waveguides implemented in material(s) that allow low loss transmission of visible light power. Light source 530 may be a laser generating light at a frequency to excite NV centers into fluorescence (e.g., 532 nm generated by an RSOA). In some embodiments, light source 530 may be comprised of a laser coupled to the photonic integrated circuit 500 via fiber/ball assisted coupling, direct edge coupling, or laser-to-chip integration. Photonic integrated circuit 500 may then convey the optical signal from the laser via a waveguide to optical modulators 520. Light source 530 may also be a laser gain chip implemented via Fabry-Perot system. Material of the gain chip may be composite III-V material such as GaN, InP, InAlGaAs, GaAs, or any other combination which emit small wavelength visible light. In some embodiments, light source 530 may also be a light-emitting diode.

With respect to waveguides or other optical components, traditional silicon waveguides are light absorbing below 1100 nm. Accordingly, photonic integrated circuit 500 may use materials allowing for the transmission of light below 1000 nm, such as silicon nitride or silicon carbide, to transmit an optical signal, such as one at 532 nm, from light source 530 through the optical modulators 520 and gratings 510 to NV Material 240.

Optical modulators 520 may be comprised of an optical modular, such as Mach Zehnder modulators or ring resonator modulators. For example, as shown in FIG. 6, laser 630 is optically coupled to Mach Zehnder modulators 620, which are then further optically coupled to gratings 610. In addition, Mach Zehnder modulators 620 may be electronically controlled by electronic control bus 640. In some embodiments, electronic control bus 640 may reside in semiconductor integrated circuit 300 and be electrically coupled to the photonic layer and further therein to Mach Zehnder modulators 620. Based on one or more control signals (e.g., as generated by electronic control bus 640), Mach Zehnder modulators 620 may adjust the output intensity of one or more members of gratings 610. Pitch spacing of such gratings may be configured to allow direct coherent emission into the color center substrate. Gratings may also be configured to be aligned to portions of the color center substrate where color center density has been enhanced or where color center orientation has been carefully controlled. In this manner, photonic integrated circuit 500 may allow for not only applying an optical signal to NV material 240, but also further providing for adjusting the intensity of the optical signal with respect to different locations across NV material 240.

As another example, as shown in FIG. 7, laser 730 is optically coupled to ring resonator modulators 720, which are then further optically coupled to gratings 710. In addition, ring resonator modulators 720 may be electronically controlled by matrix electronics control bus 740. In some embodiments, matrix electronics control bus 740 may reside in semiconductor integrated circuit 300 and be electrically coupled to the photonic layer and further therein to ring resonator modulators 720. Based on one or more control signals (e.g., as generated by matrix electronics control bus 740), ring resonator modulators 720 may adjust the output intensity of one or more members of gratings 710. In this manner, photonic integrated circuit 500 may allow for not only applying an optical signal to NV material 240, but also further providing for adjusting the intensity of the optical signal with respect to different locations across NV material 240.

In various embodiments, photonic integrated circuit 500 may also use other approaches for optical modulators 520, such as liquid crystal techniques, strain-based techniques, thermal-optical techniques, or electro-optic techniques known in the art. Also, in various embodiments, photonic integrated circuit 500 may use with respect to gratings 510 any gratings known in the art.

With respect to FIG. 8, an example of a semiconductor integrated circuit 800, which may be used to implement semiconductor integrated circuit 230, is shown that further incorporates permanent magnets 840 in addition to a Micro Generator/PLL 810, microwave antenna 820, and photodetectors 830. As shown in FIG. 9, measurements of a magnetic field at low magnetic strengths may have small response gradients and thus it may be difficult to accurately assess small changes in such a magnetic field. Accordingly, in some embodiments permanent magnets may be used to exert a static magnetic field across NV material 240. In some embodiments, an electromagnetic coil (not shown) may be further integrated into semiconductor integrated circuit 230 as a magnetic field source. In such an embodiment, the electromagnetic coil may be formed using standard multi-layer trace technology in combination with electrical vias. In either embodiment, a static magnetic field generated by permanent magnets or an electromagnetic coil may provide a magnetic bias allowing for small changes in magnetic fields at a low strength to be measured within an area of larger gradient of the ODMR response curves. In some embodiments, permanent magnets or the electromagnetic coil may be implemented in carrier PCB 210 to provide the magnetic bias as described herein.

With respect to FIG. 10, another example of an integrated device for ODMR is shown. ODMR device 1000 may be formed on a carrier PCB 1010. ODMR device 1000 may be comprised of a first layer (e.g., disposed on carrier PCB 1010) in the form of semiconductor integrated circuit 1030; a second layer disposed on the first layer in the form of an NV material 1040, wherein the second layer is optically coupled to the first layer; and a third layer disposed on the second layer in the form of photonic integrated circuit 1050, wherein the third layer is optically coupled to the second layer. ODMR device 1000 may also comprise a microwave generator and phase locked loop (Microwave Generator/PLL) 1020 electrically coupled to the third layer or integrated therein. ODMR device 1000 may also comprise a light source 1070 optically coupled to the third layer or integrated therein.

In some embodiments, semiconductor integrated circuit 1030 may be comprised in a manner similar to semiconductor integrated circuit 300 where the microwave antenna is omitted; NV material 1040 may be comprised in a manner similar to solid-state host 400; and photonic integrated circuit 1050 may be comprised in a manner similar to photonic integrated circuit 500.

In some embodiments, photonic integrated circuit 1050 may further be comprised of a metal layer deposited between photonic integrated circuit 1050 and NV material 1040 for generating microwave signals. As such, photonic integrated circuit 1050 may comprise a microwave antenna 1025 in the metal layer for transmitting microwave signals to NV material 1040. For example, the microwave antenna may be a coiled loop inductor with a resonance near 2.87 GHz. A microwave generator and phase locked loop (Microwave Generator/PLL 1020) may be electrically coupled to microwave antenna 1025. In some embodiments, Microwave Generator/PLL 1020 may be a device residing on carrier PCB 1010 and in electrical communication with microwave antenna 1025. In other embodiments, Microwave Generator/PLL 1020 may reside in one or more metal layers within semiconductor integrated circuit 1030 rather than as a device residing on carrier PCB 1010. Similarly, Microwave Generator/PLL 1020 may reside in one or more metal layers further deposited on photonic integrated circuit 1050 rather than as a device residing on carrier PCB 1010. Microwave Generator/PLL 1020 may generate microwave signals near 2.87 GHz.

While the examples herein show different ways in which a microwave antenna may reside within an integrated device for ODMR, such examples are not intended to be limiting. In a variety of embodiments, the microwave antenna may be placed anywhere within an integrated device for ODMR (e.g., in a metal layer on or within a semiconductor integrated circuit, a solid-state host, or a photonic integrated circuit) so long as it is able to affect the NV material with microwave signals as described herein.

With respect to FIG. 11, another illustrative example of an integrated device for ODMR is shown where the red fluorescence may be reflected by a mirror on one side of an NV layer such that it is detected by photodetectors deposited on or within the photonic integrated circuit. ODMR device 1100 may be formed on a carrier PCB 1110. ODMR device 1100 may be comprised of a first layer (e.g., disposed on carrier PCB 1110) in the form of semiconductor integrated circuit 1130; a second layer disposed on the first layer in the form of photonic integrated circuit 1150, wherein the second layer is optically coupled to the first layer; and a third layer disposed on the second layer in the form of an NV material 1140, wherein the third layer is optically coupled to the second layer. A reflective mirror 1190 may then be deposited on the NV material 1140. ODMR device 1100 may also comprise a microwave generator and phase locked loop (Microwave Generator/PLL) 1120 electrically coupled to the second layer. ODMR device 1100 may also comprise a light source 1170 optically coupled to the second layer or integrated therein.

In some embodiments, semiconductor integrated circuit 1130 may be comprised in a manner similar to semiconductor integrated circuit 300 where the photo detectors (or a part thereof) and microwave antenna is omitted; NV material 1140 may be comprised in a manner similar to solid-state host 400; and photonic integrated circuit 1150 may be comprised in a manner similar to photonic integrated circuit 500.

In some embodiments, photonic integrated circuit 1150 may further be comprised of a metal layer deposited between photonic integrated circuit 1150 and NV material 1140 for generating microwave signals. As such, photonic integrated circuit 1150 may comprise a microwave antenna 1125 in the metal layer for transmitting microwave signals to NV material 1140. For example, the microwave antenna may be a coiled loop inductor with a resonance near 2.87 GHz. A microwave generator and phase locked loop (Microwave Generator/PLL 1120) (not shown) may be electrically coupled to microwave antenna 1125. In some embodiments, Microwave Generator/PLL 1120 may be a device residing on carrier PCB 1110 and in electrical communication with microwave antenna 1125. In other embodiments, Microwave Generator/PLL 1120 may reside in one or more metal layers within semiconductor integrated circuit 1130 rather than as a device residing on carrier PCB 1110. Similarly, Microwave Generator/PLL 1120 may reside in one or more metal layers further deposited on photonic integrated circuit 1150 rather than as a device residing on carrier PCB 1110. Microwave Generator/PLL 1120 may generate microwave signals near 2.87 GHz.

In some embodiments, photodetectors 1195 may be placed in or on photonic integrated circuit 1150 and electrically coupled to any supporting circuitry in semiconductor integrated circuit 1130. In such an embodiment, metamaterial filter 1180 may reside in a semiconductor layer deposited between NV material 1140 and photonic integrated circuit 1150. In some embodiments, photodetectors may be placed in semiconductor integrated circuit 1130 with the metamaterial filter in: (i) a semiconductor layer deposited between NV material 1140 and photonic integrated circuit 1150; or (ii) the semiconductor integrated circuit 1130.

Detailed embodiments are disclosed herein. However, it is to be understood that the disclosed embodiments are intended only as examples. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the aspects herein in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting but rather to provide an understandable description of possible implementations. Various embodiments are shown in FIGS. 1-11, but the embodiments are not limited to the illustrated structure or application.

Herein, designations such as “first” or “second” are arbitrary and do not signify priority or importance. Rather, they are used to refer to particular elements among a plurality of elements of the same type (e.g., a set of waveguides, a set of temperatures, a set of refractive indexes, etc.).

The terms “a” and “an,” as used herein, are defined as one or more than one. The term “plurality,” as used herein, is defined as two or more than two. The term “another,” as used herein, is defined as at least a second or more. The terms “including” and/or “having,” as used herein, are defined as comprising (i.e. open language). The phrase “at least one of . . . and . . . ” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. As an example, the phrase “at least one of A, B, and C” includes A only, B only, C only, or any combination thereof (e.g. AB, AC, BC or ABC).

As used herein, “cause” or “causing” means to make, command, instruct, and/or enable an event or action to occur or at least be in a state where such event or action may occur, either in a direct or indirect manner.

Aspects herein can be embodied in other forms without departing from the spirit or essential attributes thereof. Accordingly, reference should be made to the following claims rather than to the foregoing specification, as indicating the scope hereof.